1. Field of the Invention
The present invention relates to a semiconductor device such as a power semiconductor module and a method of fabricating the same.
2. Description of the Background Art
FIG. 15 is a plan view of a mounted major part of a conventional semiconductor device 200. FIG. 16 is a schematic front elevation of the semiconductor device 200 as viewed in the direction of the arrow A1 of FIG. 15. Referring to FIGS. 15 and 16, the semiconductor device 200 comprises a plurality of semiconductor bodies 1; insulating substrates 3 provided with metal patterns 4a to 4e; a heat sink 6; external electrodes 8; and wires 9.
The conventional semiconductor device 200 is fabricated in a manner to be described hereinafter. The insulating substrates 3 provided with the metal patterns 4a to 4e mounted on the top surface thereof and a metal layer mounted on the bottom surface thereof are placed on the heat sink 6. The semiconductor bodies 1 are placed horizontally on the insulating substrates 3 to be bonded to the insulating substrates 3 with a soldering material (not shown) such as solder. After the semiconductor bodies 1 are mounted, the wires 9 made of, for example, aluminum connect the semiconductor bodies 1 to the metal patterns 4b, 4c, 4d, 4c, whereby the metal patterns 4b, 4c, 4d, 4e serve as electrodes of the semiconductor bodies 1. When the semiconductor bodies 1 are bipolar transistors, the metal patterns 4a, 4b, 4c serve as collector, emitter, base electrodes, respectively, and the metal patterns 4d and 4e serve as relay electrodes. Then the respective external electrodes 8 are joined to the metal pattern electrodes 4a, 4b, 4c. The mount assembly provided in the foregoing manner is subjected to resin seal and the like, so that the semiconductor device 200 is provided.
In the conventional semiconductor device 200, the semiconductor bodies 1 are disposed horizontally. When the semiconductor device 200 is operated, the heat generated by the respective semiconductor bodies 1, if provided in multiplicity as shown in FIG. 15, acts synergistically to exceed the heat sink capability of the semiconductor device 200. The disadvantage of the conventional semiconductor device 200 is that it is thermally broken after prolonged use.
Another disadvantage is the increasing size of the large-capacity semiconductor device having a large number of semiconductor bodies because of the horizontal arrangement of the semiconductor bodies.